I have put together a detailed video on crew skills. I talk about training your crew to 100% and then talk about each of the crew skills that can be further researched by tank type. Keep in mind these skills apply to all tanks. My recommendation is to focus on the medium and TD skills, meaning try to play more games in those two types of tanks. Of course there are some good skills under the lights and mediums, so don't forget about them. But the main point is that it is important to choose these skills wisely at the start as they can make a big difference in game.

If you want to really grind skills fast, play elite tanks, use premium certificates and the free crew XP (and possibly combat XP) boosters, hit multipliers (they stack with the boosters), and dump your elite XP into acceleration. If you go crazy during a high multiplier weekend, you can grind out enormous amounts of crew XP with those ideas. Mentor is mostly a relic IMO. Yes, it helps a bit, but getting effectively 5K to 10K crew XP per win because of boosters and active multipliers and acceleration totally dwarfs having an extra 5% or 7% from mentor. If you do want to train mentor to level 3 or 4 that's fine (because the low levels are fairly cheap), but don't take mentor to level 7 and only then start working on your other medium skills.

If you want to really grind skills fast, play elite tanks, use premium certificates and the free crew XP (and possibly combat XP) boosters, hit multipliers (they stack with the boosters), and dump your elite XP into acceleration. If you go crazy during a high multiplier weekend, you can grind out enormous amounts of crew XP with those ideas. Mentor is mostly a relic IMO. Yes, it helps a bit, but getting effectively 5K to 10K crew XP per win because of boosters and active multipliers and acceleration totally dwarfs having an extra 5% or 7% from mentor. If you do want to train mentor to level 3 or 4 that's fine (because the low levels are fairly cheap), but don't take mentor to level 7 and only then start working on your other medium skills.

If you want to really grind skills fast, play elite tanks, use premium certificates and the free crew XP (and possibly combat XP) boosters, hit multipliers (they stack with the boosters), and dump your elite XP into acceleration. If you go crazy during a high multiplier weekend, you can grind out enormous amounts of crew XP with those ideas. Mentor is mostly a relic IMO. Yes, it helps a bit, but getting effectively 5K to 10K crew XP per win because of boosters and active multipliers and acceleration totally dwarfs having an extra 5% or 7% from mentor. If you do want to train mentor to level 3 or 4 that's fine (because the low levels are fairly cheap), but don't take mentor to level 7 and only then start working on your other medium skills.

Ya I think this is it. It’s really about getting a key set of skills to level 5 first. If you do this, you don’t need level 7 Mentor. You only need level 7 Mentor when you’re taking your skills beyond level 5 because the top two levels require two thirds of the overall experience to get to level 7.

This is also really woke me up as to how much gold I’ve wasted on other things, when I should have been spending it on accelerating the top two levels of crew skills (about 4k gold for each skill), since it affects the performance of all of your tanks.